ABB RELION REX640 Technical Manual page 1164

Section 5
Protection related functions
1158
Bus A
~
3
CB_A
Z2_START
GUID-8721166F-6135-40E0-9867-D350F7B4813D V1 EN
Figure 625: Simplified functional diagram of the permissive underreach scheme
Permissive overrreaching transfer trip scheme POTT
The permissive overreach scheme is enabled with Scheme type = "Permissive
Overreach".
In this scheme, the START signal from the overreaching residual overcurrent function
DEFLPDEF is connected to the CSOR input to create a CS_PRM signal. The CS_PRM
signal can also be issued simultaneously from the underreaching residual overcurrent
function DEFHPDEF. In this case, the start signal from the underreaching function is
connected to the CSUR input. The duration of the CSUR input signal can be prolonged
by the Carrier Min Dur setting to ensure a sufficient duration of the CS_PRM signal.
In case of parallel feeders, when the external current reversal logic
(RCRWPSCH) is enabled, the CS_PRM signal is not prolonged and
the value of Carrier Min Dur is set to zero to secure correct operation.
In the permissive overreach scheme, the received signal CR_PRM or CRL, if the
unblocking function is enabled, is used to allow the overreaching residual overcurrent
function DEFLPDEF to trip (activation of the OPERATE output) after the settable
pick-up delay Coordination time. The start signal from the overreaching zone is
connected to the CACC input.
The CS_PRM signal is also generated if the CR_PRM signal is received and the local
carrier acceleration signal CACC is active.
Activating the BLOCK input totally blocks the permissive overreach scheme. The
CS_PRM and OPERATE outputs can be blocked by the BLK_CS_OPR input.
CB_B
TRIP_CB_A
DEFL_START
DEFH_START
1MRS759142 C
Bus B
~
3
TRIP_CB_B
REX640
Technical Manual